''Genicanthus bellus'', the ornate angelfish, bellus angelfish or bellus lyretail angelfish, is a species of marine

ray-finned fish Actinopterygii (; ), members of which are known as ray-finned fishes, is a class of bony fish. They comprise over 50% of living vertebrate species. The ray-finned fishes are so called because their fins are webs of skin supported by bony or hor ...

, a

marine angelfish Marine angelfish are perciform fish of the family Pomacanthidae. They are found on shallow reefs in the tropical Atlantic, Indian, and mostly western Pacific Oceans. The family contains seven genera and about 86 species. They should not be confu ...

belonging to the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Pomacanthidae Marine angelfish are perciform fish of the family Pomacanthidae. They are found on shallow reefs in the tropical Atlantic, Indian, and mostly western Pacific Oceans. The family contains seven genera and about 86 species. They should not be confu ...

. It is found in the

Indo-Pacific The Indo-Pacific is a vast biogeographic region of Earth. In a narrow sense, sometimes known as the Indo-West Pacific or Indo-Pacific Asia, it comprises the tropical waters of the Indian Ocean, the western and central Pacific Ocean, and the ...

region.

Description

''Genicanthus bellus'' Is

sexually dichromatic Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most anim ...

, the males and females show different colouration and patterning. The females, and the juveniles, have greyish to bluish background colouration and are marked with wide black bands and a blue longitudinal stripe on the lower flanks. The males’ background colour is pale bluish to greyish and they have horizontal golden stripes along the centre of the flanks and another along the lower back. Also in the males the bases of the

pectoral Pectoral may refer to: * The chest region and anything relating to it. * Pectoral cross, a cross worn on the chest * a decorative, usually jeweled version of a gorget * Pectoral (Ancient Egypt), a type of jewelry worn in ancient Egypt * Pectoralis ...

and

dorsal fin A dorsal fin is a fin located on the back of most marine and freshwater vertebrates within various taxa of the animal kingdom. Many species of animals possessing dorsal fins are not particularly closely related to each other, though through conv ...

s are the same colour as the stripes on the body. The

caudal fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as se ...

are unpigmented frequently marked with patches of orange, these have filamentous extensions and are bright blue. The lips are also bright blue. In the females and juveniles there is a black stripe which runs vertically from the nape through and engulfing the eye but does not extend past the lower part of the

orbit In celestial mechanics, an orbit is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an object or position in space such as a p ...

. A second black stripe begins immediately to the rear of the first, creating a right angle at the origin of the dorsal fin and the continuing along that fins base. Another black stripe commences at the right angle of the second stripe and runs diagonally downward to the lower lobe of the caudal fin. The last black stripe runs along the upper margin of the upper lobe of the dorsal fin, starting at the caudal peduncle. Each of these four stripes has margins of white or very pale blue. The colour of the

anal fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as se ...

varies and it may have either a double or single orange stripe at the margin, however, this stripe can also be absent. is rather variable, and is edged either with a single or double stripe in orange. The dorsal fin is normally largely black, but in the largest and oldest females this fin may show variable shades of r. There are two silvery-white dots on the black upper lips of the females too. The dorsal fin contains 15 spines and 15-16 soft rays while the anal fin has 3 spines and 16-17 soft rays. This species attains a maximum

total length Fish measurement is the measuring of individual fish and various parts of their anatomies. These data are used in many areas of ichthyology, including taxonomy and fisheries biology. Overall length * Standard length (SL) is the length of a fish ...

of .

Distribution

''Genicanthus bellus'' has a wide but localised distribution in the western Pacific Ocean and eastern Indian Ocean. In the Pacific it has been recorded from

Tahiti Tahiti (; Tahitian ; ; previously also known as Otaheite) is the largest island of the Windward group of the Society Islands in French Polynesia. It is located in the central part of the Pacific Ocean and the nearest major landmass is Austr ...

Guam Guam (; ch, Guåhan ) is an organized, unincorporated territory of the United States in the Micronesia subregion of the western Pacific Ocean. It is the westernmost point and territory of the United States (reckoned from the geographic cent ...

, Palau, Tonga, the

Cook Islands ) , image_map = Cook Islands on the globe (small islands magnified) (Polynesia centered).svg , capital = Avarua , coordinates = , largest_city = Avarua , official_languages = , lan ...

, the

Marshall Islands The Marshall Islands ( mh, Ṃajeḷ), officially the Republic of the Marshall Islands ( mh, Aolepān Aorōkin Ṃajeḷ),'' () is an independent island country and microstate near the Equator in the Pacific Ocean, slightly west of the Internati ...

, the Philippines, southern Japan and southern Indonesia. It’s preference for quite deep water may mean that this species is under recorded. In Australian waters it is found in the Indian Ocean of the

Cocos (Keeling) Islands ) , anthem = "''Advance Australia Fair''" , song_type = , song = , image_map = Australia on the globe (Cocos (Keeling) Islands special) (Southeast Asia centered).svg , map_alt = Location of the Cocos (Keeling) Islands , map_caption = ...

and

Christmas Island Christmas Island, officially the Territory of Christmas Island, is an Australian external territory comprising the island of the same name. It is located in the Indian Ocean, around south of Java and Sumatra and around north-west of the ...

, as well as Holmes Reef in the

Coral Sea The Coral Sea () is a marginal sea of the South Pacific off the northeast coast of Australia, and classified as an interim Australian bioregion. The Coral Sea extends down the Australian northeast coast. Most of it is protected by the Fre ...

Habitat and biology

''Genicanthus bellus'' is found at depths between . Here it lives on deep reefs, frequently in areas which are swept by strong currents on the outer drop offs. It is a sociable species which lives in schools, within these there are

harems Harem (Persian: حرمسرا ''haramsarā'', ar, حَرِيمٌ ''ḥarīm'', "a sacred inviolable place; harem; female members of the family") refers to domestic spaces that are reserved for the women of the house in a Muslim family. A hare ...

of 3-7 fish, although the mating system has been described as being more like

lekking A lek is an aggregation of male animals gathered to engage in competitive displays and courtship rituals, known as lekking, to entice visiting females which are surveying prospective partners with which to mate. A lek can also indicate an avail ...

. All angelfish are sequential

protogynous hermaphrodites Sequential hermaphroditism (called dichogamy in botany) is a type of hermaphroditism that occurs in many fish, gastropods, and plants. Sequential hermaphroditism occurs when the individual changes its sex at some point in its life. In particular, ...

, all newly adult fish are female but the dominant females can increase the production of

testosterone Testosterone is the primary sex hormone and anabolic steroid in males. In humans, testosterone plays a key role in the development of Male reproductive system, male reproductive tissues such as testes and prostate, as well as promoting secondar ...

in the absence of a male and change sex to male in as short a time as a

fortnight A fortnight is a unit of time equal to 14 days (two weeks). The word derives from the Old English term , meaning "" (or "fourteen days," since the Anglo-Saxons counted by nights). Astronomy and tides In astronomy, a ''lunar fortnight'' is h ...

. They feed mainly on plankton, forming shoals in midwater to feed. This species will also feed on benthic invertebrates like polychaetes and bryozoans, as well as algae.

Systematics

''Genicanthus bellus'' was first formally described in 1979 by the American ichthyologist John Ernest Randall (1924-2020) with the type locality given as “Outside barrier reef off District of Paea, Tahiti, Society Islands, depth 60 m.” The specific name ''bellus'' means “beautiful”. The ornate angelfish is only known to hybridise with the blackstriped angelfish (''

Genicanthus lamarck ''Genicanthus lamarck'', the blackstriped angelfish or Lamarck's angelfish, is a species of marine ray-finned fish, a marine angelfish belonging to the family Pomacanthidae. It occurs in the Indo-West Pacific region. Description ''Genicanthu ...

'').

Utilisation

Genicanthus bellus is very infrequent and fetches high prices in the aquarium trade as it is rarely collected because of the depths at which it lives. It is some times more numerous in the trade when collecting effort is increased. There can be high mortality in specimens collected for the trade but healthy, acclimated fish can be very hardy and resilient in captivity.

References

{{Taxonbar, from=Q744838 bellus Fish described in 1975